Each of various kinds of electrical devices mounted on a vehicle is connected to a wire harness for transmitting signals outputted from a power supply, a ground, an ECU, and the like, through a connector. Additionally, there is also required, as an electrical wiring device for the vehicle, auxiliary connectors for connection with optional devices, such as a navigation device (sec PTL 1 (JP 2003-252131 A)).
FIG. 3 is an explanatory view illustrating auxiliary connectors as the electrical wiring device for the vehicle according to the conventional example and various kinds of optional devices for connection with the auxiliary connectors. The example illustrated in FIG. 3 illustrates the electrical wiring device 100 for the vehicle, which is intended to connect with four optional devices N1-N4. The electrical wiring device 100 of the conventional example includes wire harnesses 102 for connection with the respective optional devices N1-N4 and auxiliary connectors 101 for connection with the respective wire harnesses.
The optional device N1 requires, besides signals of power supply (+B) and ground (GND), and also respective signals of ignition (IG), accessories (ACC), illuminations (ILL), speed (SPD), and backward travelling (R). Thus, there is a need for a wire harness for connection with these seven signals and also the number of connectors corresponding to the wire harness. That is, a plurality of connectors for power supply and signal supply are used in accordance with the optional devices to be mounted on the vehicle.
Meanwhile, the optional device N2 requires a wire harness for connection with three signals since it requires signals of power supply (+B), ground (GND), and ignition (IGN). Also, there is a need for the number of connectors corresponding to the wire harness.